Consequently, he wrote a respective report to the Institute[clarification needed], stressing the Kets’ poor living conditions and suggesting federal aid.
[citation needed] Vainshtein also decided to undertake a second expedition in 1949, when he established that the Kets consisted of two tribes, whose northern branch were likely those whose ancestors had migrated across the land bridge of the then-dry Bering Strait into America some 12,000 years ago.
], he had reached the territory of what today is Tuva, another region of Siberia which ethnologically and archaeologically represented an almost complete unknown area (terra incognita) on the Soviet Union's map.
[citation needed] A few days later, he visited Vainshtein again, returning his diaries and strongly encouraging him to someday write a book about his personal experiences, including intriguing details from his expeditions into Central Asia.
[citation needed] In the late 1990's, the Russian filmmaker Leonid Kruglov visited Vainshtein proposing to produce a film about his expeditions into Tuva, using as a "red line" Vainshtein's correspondence with American Nobel laureate Richard Feynman, who had written him a letter in 1981 requesting his help in securing a visa to visit Tuva, which had not been granted during Feynman's lifetime.
[citation needed] To make the documentary, Kruglov and his film crew travelled on the backs of horses and reindeer to reach the places in Tuva which Vainshtein had visited and researched.
During the many months of filming, Kruglov also managed to reach a mysterious location high up in the taiga of the eastern Sayan Mountains, which Vainshtein had once tried but failed to visit: the Arshan-Tschoigan mineral springs, reputed to have healing powers.
The author was invited to hold scientific lectures about Siberian peoples, especially about Tuvans and their tradition of shamanism, at the Universities of Moscow, Novosibirsk and Cambridge, but also at educational institutions in Germany, Finland, France, Sweden, Japan and the USA.
Under the close guidance of Sevyan Vainshtein, this book was first published in German, with the title Geheimnisvolles Tuwa – Expeditionen in das Herz Asiens, Oststeinbek 2005/2006, along with a DVD featuring Leonid Kruglov's aforementioned documentary as well as many of his photos, and examples of the famous Tuvan throat singing.
[citation needed] The book's Russian version, again under the close guidance of the author, was finally produced with the personal help and support of the Tuvan representative of the State Duma, deputy Larisa Shoigu and some of her friends[who?